This invention relates to a transmission for use in an automotive vehicle, and more particularly to a transmission equipped with a reverse mechanism.
In a conventional transmission equipped with a reverse mechanism for use in a three-wheeled or four-wheeled buggy car, etc., a forward shift drum rotated by a first operating element and a reverse shift drum rotated by a second operating element are separately supported within the transmission. Upon rotation of each of these forward and reverse shift drums, shift forks engaged in lead grooves in the outer peripheral surface of the drums shift, so that forward and reverse gears are brought into driving engagement with a drive shaft by means of shifters integrally mounted to the shift forks.
However, a transmission having a forward and a reverse shift drums separately supported therein is increased in size. In view of the foregoing, the present assignee has proposed in its U.S. patent application Ser. No. 946,359 filed on Dec. 14, 1986, now U.S. Pat. No. 4,713,979 that the forward shift drum and the reverse shift drum are concentrically overlapped with each other in order to reduce the size of the transmission.
However, each of the shift drums is required to be provided with a rotation positioning mechanism in order to regulate the rotary position for moving a predetermined shift fork. Accordingly, in the case the forward and the backward shift drums are overlapped, it becomes a problem how and where to provide these rotation positioning mechanisms to the respective shift drums. Furthermore, it is desirable that these rotation positioning mechanisms are provided in such a fashion as to facilitate a maintenance.